GLYCOSIDASE INHIBITORS AND METHODS OF SYNTHESIZING SAME

INHIBITEURS DE GLYCOSIDASES ET PROCEDES DE SYNTHESE DE CEUX-CI

English Abstract

A method for synthesizing Salacinol, its stereoisomers, and non-naturally
occurring selenium and nitrogen analogues thereof having formula (I). The
compounds are potentially useful as glycosidase inhibitors. The synthetic
schemes comprise reacting a cyclic sulfate with a 5-membered ring sugar
containing a heteroatom (X). The heteroatom preferably comprises sulfur,
selenium, or nitrogen. The cyclic sulfate and ring sugar reagents may be
readily prepared from carbohydrate precursors, such as D-glucose, L-glucose, D-
xylose and L-xylose. The target compounds are prepared by opening of the
cyclic sulfates by nucleophilic attack of the heteroatoms on the 5-membered
ring sugars. The resulting heterocyclic compounds have a stable, inner salt
structure comprising a heteroatom cation and a sulfate anion. The synthetic
schemes yield various stereoisomers of the target compounds in moderate to
good yields with limited side-reactions. In an alternative embodiment of the
invention, the cyclic sulfate may be similarly reacted with a 6-membered ring
sugar containing a heteroatom (X) to yield a compound having formula (XII).

French Abstract

L'invention concerne une méthode de synthèse du Salacinol, de ses stéréoisomères, et de ses analogues de sélénium et d'azote non naturels représentés par la formule (I). Ces composés sont des inhibiteurs potentiels de glycosidase. Les procédés de synthèse consistent à faire réagir un sulfate cyclique avec un sucre cyclique à cinq chaînons contenant un hétéroatome (X). L'hétéroatome comprend, de préférence, du soufre, du sélénium, ou de l'azote. Le sulfate cyclique et les réagents du sucre cyclique peuvent être facilement préparés à partir de précurseurs de carbohydrate, par exemple D-glucose, L-glucose, D-xylose et L-xylose. Les composés cibles sont préparés par ouverture des sulfates cycliques par attaque nucléophile des hétéroatomes sur des sucres cycliques à cinq chaînons. Les composés hétérocycliques obtenus possèdent une structure de sel interne stable comprenant un cation d'hétéroatome et un anion de sulfate. Les procédés de synthèse permettent d'obtenir des productions, de modérées à bonnes, de divers stéréoisomères des composés cibles avec des réactions secondaires limitées. Dans un autre mode de réalisation de l'invention, le sulfate cyclique peut, de manière semblable, être mis en réaction avec un sucre cyclique à 6 chaînons contenant un hétéroatome (X) afin d'obtenir un composé représenté par la formule (XII).

Claims

WHAT IS CLAIMED IS:
1. A compound selected from the group consisting of compounds
represented by the formula (I) and stereoisomers and pharmaceutically
acceptable salts
thereof:
<IMG>
wherein X is selected from the group consisting of S, Se and NH; R1, R2, R3 ,
R4 and R5
are the same or different and are selected from the group consisting of H, OH,
SH, NH2,
and halogens; and R6 is selected from the group consisting of H, OH and alkyl,
alkenyl,
alkynyl, aryl, and alkoxy substituents comprising between 1-4 carbon atoms,
said compound excluding naturally occurring Salacinol and Kotalanol having the
structures (A) and (B)
<IMG>
31

2. A pharmaceutical composition comprising a
compound according to claim
1 together with a pharmaceutically acceptable carrier.
3. The compound as defined in claim 1,
wherein R1, R2, R3, R4 and R6 are OH
and R5 is H.
4. The compound as defined in claim 1,
wherein R1, R2, R3, R4 and R5 are OH
and R6 is an alkoxy substituent.
5. A process for the production of a compound
of having the formula (IA)
<IMG>
comprising the steps of:
(a) providing a cyclic sulfate having the formula (II)
<IMG>
wherein R1 and R2 are H or a protecting group and R3 is selected from the
group consisting of H and alkyl, alkenyl, alkynyl, aryl, polyhydroylated32

alkyl and alkoxy substituents comprising between 1-4 carbon atoms and
protected derivatives of polyhydroylated alkyl and alkoxy substituents;
(b) providing a 5-membered sugar of the formula (III),
<IMG>
wherein X is selected from the group consisting of S, Se, and NH and R4,
R5 and R6 are OH or a protected OH group;
(c) reacting the cyclic sulphate (II) with the 5-membered ring sugar (III)
to
produce an intermediate compound having an internal salt structure
comprising a positively charged heteroatom X and a negatively charged
sulfate counterion; and
(d) removing any protecting groups from said intermediate compound.
6. The process as defined in claim 5, wherein said cyclic sulfate is a 2,4-
di-
O-protected-D-or L-erythritol-1,3-cyclic sulfate.
7. The process as defined in claim 5, wherein said cyclic sulfate is 2,4-0-
Benzylidene-D-or L-erythritol-1,3-cyclic sulfate.
8. The process as defined in claim 5, wherein R3 is a protected
polyhydroxylated alkyl chain comprising between 1-4 carbon atoms.
33

9. The process as defined in claim 5, wherein R4, R5, and R6 are selected
from the group consisting of OH and OCH2C6H5.
10. The process as defined in claim 5, wherein the reaction is carried out
in a
solvent selected from the group consisting of acetone and methanol.
11. The process as defined in claim 10, further comprising the step of
adding a
base to said solvent.
12. The process as defined in claim 11, wherein said base is K2CO3.
13. The process as defined in claim 5, wherein the removal of the protecting
groups is performed by hydrogenolysis of said intermediate compound.
14. A non-naturally occurring stereoisomer of Salacinol selected from the
group consisting of compounds (IV) and (V)
<IMG>
15. A pharmaceutical composition comprising a compound according to claim
14 together with a pharmaceutically acceptable carrier.
16. A process for the production of a compound having the formula (VI)
comprising reacting a cyclic sulfate selected from the group consisting of
compounds
having the formulas (VII) and (VIII) with a sugar compound having the formula
(IX)
where R = H, CH2C6H5, CH2C6H4-OMe p., or COR2 where R2 =CH3:
34

<IMG>
17. A non-naturally occurring nitrogen analogue of Salacinol selected from
the group consisting of compounds having the structures (2) and (32)
<IMG>
35

18. A pharmaceutical composition comprising a compound according to claim
17 together with a pharmaceutically acceptable carrier.
19. A non-naturally occurring selenium analogue of Salacinol selected from
the group consisting of compounds having the structures (3) and (29)
<IMG>
20. A pharmaceutical composition comprising a compound according to claim
19 together with a pharmaceutically acceptable carrier.
21. A process for the production of a compound of having the formula (e)
<IMG>
comprising reacting a cyclic sulfate having the general formula (II) with a 5-
membered ring sugar having the formula (III)
36

<IMG>
wherein the cyclic sulfate (II) is opened by nucleophilic attack of the
heteroatom X on the
sugar (III), where X is selected from the group consisting of S, Se, and NH;
R1 and R2 are
selected from the group consisting of H and a protecting group; R3 is selected
from the
group consisting of H and alkyl, alkenyl, alkynyl, aryl, polyhydroylated alkyl
and alkoxy
substituents comprising between 1-4 carbon atoms; and R4, R5 and R6 are the
same or
different and are selected from the group consisting of halogens, H, OH, SH,
NH2, and
protected derivatives of OH, SH, or NH2.
22. The process of claim 21 for synthesis of a compound having structure
(1)
comprising the steps set forth in either of Schemes 7 or 10:
<IMG>
Scheme 7
37

<IMG>
Scheme 10.
23 The process of claim 21 for synthesis of a compound having structure
(23)
comprising the following steps set forth in Scheme 8:
<IMG>
Scheme 8.
24. The process of claim 21 for synthesis of a compound having structure
(25)
comprising the following steps set forth in Scheme 9.
<IMG>
Scheme 9
38

25. The process of claim 21 for synthesis of a selenium analogue of
Salacinol
having structure (3) or (29) comprising the following steps set forth in
either of Schemes
11 or 12:
<IMG>
R = H, CH2C6H5, CH2C6H4-OMep
Scheme 11
<IMG>
R = H, CH2C6H5, CH2C6H4-OMep
Scheme 12.
26. The process of claim 21 for synthesis of a nitrogen analogue of
Salacinol
having structure (2) or (32) comprising the following steps set forth in
either of Schemes
13 or 14:
39

<IMG>
Scheme 13
<IMG>
Scheme 14.
27. The process of claim 5, wherein said protecting group is selected from
the
group consisting of benzyl and benzylidene formed by linking R1 and R2
together.
28. The process of claim 21, wherein said protecting group is selected from
the group consisting of benzyl and benzylidene formed by linking R1 and R2
together.
29. A compound selected from the group consisting of compounds
represented by the formula (I) and stereoisomers and pharmaceutically
acceptable salts
thereof:
40

<IMG>
wherein X is selected from the group consisting of S, Se and NH; R1, R2, R3
and R4 are
the same or different and are selected from the group consisting of H, OH, SH,
NH2, and
halogens; R5 is selected from the group consisting of H and CH(OH)-CH(OH)-
C(OH)H2,
and R6 is selected from the group consisting of OH and alkyl, alkenyl,
alkynyl, aryl, and
alkoxy substituents,
said compound excluding naturally occurring Salacinol and Kotalanol having the
structures (A) and (B)
<IMG>
30. The use of a composition as defined in any one of claims 2, 15, 18 or
20
for treatment of a carbohydrate metabolic disorder, said composition
comprising an
effective amount of said compound for such use.
31. The use as defined in claim 30 wherein said carbohydrate metabolic
disorder is non-insulin dependent diabetes.
41

32. A compound selected from the group consisting of compounds
represented by the formula (I) and stereoisomers and pharmaceutically
acceptable salts
thereof:
<IMG>
wherein X is selected from the group consisting of S, Se and NH; R1, R2, R3 R4
and R5
are the same or different and are selected from the group consisting of H, OH,
SH, NH2,
and halogens; and R6 comprises an alkoxy substituent having between 1-4 carbon
atoms,
said compound excluding naturally occurring Salacinol and Kotalanol having the
structures (A) and (B)
<IMG>
33. A compound selected from the group consisting of compounds
represented by the formula (I) and stereoisomers and pharmaceutically
acceptable salts
thereof:
42

<IMG>
wherein X is selected from the group consisting of S, Se and NH; R1, R2, R3 ,
R4 and R5
are OH and R6 is CH(OH)-CH(OH)-C(OH)H2,
said compound excluding naturally occurring Salacinol and Kotalanol having the
structures (A) and (B)
<IMG>
43

Description

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GLYCOSIDASE INHIBITORS AND METHODS OF SYNTHESIZING SAE
Technical Field
s
This application relates to methods for synthesizing Salacinol, its
stereoisomers, and analogues thereof potentially useful as glycosidase
inhibitors.
~o Background
In treatment of non-insulin dependent diabetes (NIDD)
management of blood glucose levels is critical. One strategy for treating
NIDD is to delay digestion of ingested carbohydrates, thereby lowering post-
Is prandial blood glucose concentration. This can be achieved by administering
drugs which inhibit the activity of enzymes, such as glucosidases,. which
mediate the hydrolysis of complex starches to oligosaccharides in the small
intestine. For example, carbohydrate analogues, such as acarbose,
reversibly inhibit the function of pancreatic a-amylase a.nd membrane-bound
2o intestinal a-glucoside hydrolase enzymes. In patients suffering from Type
II
diabetes, such enzyme inhibition results in delayed glucose absorption into
the blood and a smoothing or Powering of postprandial hyperglycemia,
resulting in improved glycemic control.
2s Some naturally-occurring glucosidase inhibitors have been
isolated from Salacia reticulate, a plant native to submontane forests in Sri
Lanka and parts of India (known as "Kotala himbutu" in Singhalese). Salacia
reticulate is a woody climbing plant which has been used in the Ayurvedic
system of Indian medicine in the treatment of diabetes. Traditionally,
3o Ayurvedic medicine advised that a person suffering from diabetes should
drink water left overnight in a mug carved from Kotala himbutu wood. In an
article published in 1997, Yoshikawa et al. reported the isolation of the
compound Salacinol from a water-soluble fraction derived from the dried roots
and stems of Salacia reticulata.~ Yoshikawa et al. determined the structure of
-1-
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Salacinol, shown below, and demonstrated its efficacy as an a-glucosidase
inhibitor.
HO
s /1
~~ OH
+S 03S0
HO
HO~
OH
Salacinol
~CgH 1 gOgS2~
Yoshikawa et al. later reported the isolation from the roots and
stems of Salacia reticulate of Kotalanol which was also shown to be effective
is as an a-glucosidase inhibitor.2 Like Salicinol, Kotalanol contains a
thiosugar
sulfonium ion and an internal sulfate providing the counterion:
HO OH OH
OH
20 ~ a
+S 03S0 OH
HO
H O
OH
2s Kotalanol
~C12H24~1252~
Kotalanol has been found to show more potent inhibitory activity against
sucrase than Salicinol and acarbose.2
The exact mechanism of action of Salacinol and other
glucosidase inhibitors has not yet been elucidated. Some known glycosidase
-2-
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inhibitors, ~ such as the indolizidine alkaloid's castahos~~rrpine and
swainsonine, are known to carry a positive charge at physiological pH.
s
HO
H
OH
Castanospermine
HO OH
is OH
Swainsonine
It is believed that the mechanism of action of some known inhibitors may be at
least partially explained by the establishment of stabilizing electrostatic
interactions between the inhibitor and the enzyme active site carboxylate
residues. It is postulated that the compounds of the present invention, which
2s comprise postively charged sulfonium, ammonium, and selenonium ions,
could function in a similar manner. It is also possible that Salacinol and
other
compounds of the same class may act by alteration of a transport mechanism
across the intestinal wall rather than by directly binding to glucosidase
enzymes.
Salacinol and Kotalanol may potentially have fewer long-term
side effects than other existing oral antidiabetic agents. For example, oral
administration of acarbose in the treatment of Type II diabetes results in
-3-
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undesirable gastrointestinal side effects in some patients, most notably
increased flatulence, diarrhoea and abdominal pain. As mentioned above,
Salacinol has been used as a therapy for diabetes in the Ayurvedic system of
traditional medicine for many years with no notable side effects reported.
s Further, recent animal studies have shown that the oral ingestion of an
extractive from a Salacia reticulate trunk at a dose of 5,000 mg/kg had no
serious acute toxicity or mutagenicity in rats.3
The Salacia reticulate plant is, however, in relatively small
to supply and is not readily available outside of Sri Lanka and India.
Accordingly, it would be desirable if Salicinol, Kotalanol and analogues
thereof
could be produced synthetically.
Carbohydrate processing inhibitors have also been shown to be
is effective in the treatment of some non-diabetic disorders, such as cancer.
While normal cells display characteristic oligosaccharide structures, tumor
cells display very complex structures that are usually found in embryonic
tissues. It is believed that these complex structures provide signal stimuli
for
rapid proliferation and metastasis of tumor cells. A possible strategy for
2o therapeutic use of glucosidase inhibitors is to take advantage of the
differential rates of normal vs cancer cell growth to inhibit assembly of
complex oligosaccharide structures. For example, the indolizidine alkaloid
swainsonine, an inhibitor of Golgi a-mannosidase II, reportedly reduces tumor
cell metastasis, enhances cellular immune responses, and reduces tumor cell
2s growth in mice.4 Swainsonine treatment has led to significant reduction of
tumor mass in human patients with advanced malignancies, and is a
promising drug therapy for patients suffering from breast, liver, lung and
other
malignancies.5~6
3o The compounds of the present invention may also find
application in the treatment of Alzheimer's disease due to their stable,
internal
salt structure. Alzheimer's is characterized by plaque formation in the brain
caused by aggregation of a peptide, ~i-amyloid, into fibrils. This is toxic to
-4-
SUBSTITUTE SHEET (RULE 26)

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neuronal cells. One can inhibit this aggregation by using detergent-dike
molecules. It is believed that the compounds of the present invention, which
are amphipathic, may demonstrate this activity.
s The need has therefore arisen for a new class of glycosidase
inhibitors which may be synthesized in high yields from readily available
starting materials and which have potential use as therapeutics.
Summary of the Invention
to
In accordance with the invention, a compound selected from the
group consisting of non-naturally occurring compounds represented by the
general formula (I), including stereoisomers and pharmaceutically acceptable
salts thereof is disclosed,
is
Ra R5
Rs
-I- x oso 3
R3
Rz R~
where X is selected from the group consisting of S, Se, and NH. Such
compounds include stereoisomers of Salicinol. The target compounds have a
2s stable, internal salt structure comprising heteroatom cation X and a
sulfate
anion; the substituents may vary without departing from the invention.
Preferably, R~, R2, R3, R4 and R5 are the same or different and are selected
from the group consisting of H, OH, SH, NH2, halogens and constituents of
compounds selected from the group consisting of cyclopropanes, epoxides,
3o aziridines and episulfides; and R6 is selected from the group consisting of
H
and optionally substituted straight chain, branched, or cyclic, saturated or
unsaturated hydrocarbon radicals, such as alkyl, alkenyl, alkynyl, aryl, and
alkoxy substituents containing any suitable functionality.
-5-
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Processes for the production of compounds of the general
formula (I) are also disclosed comprising reacting a cyclic sulfate having the
general formula (II) with a 5-membered ring sugar having the general formula
(III)
Rs
X
4
Rz~ 2 R6
_3 O
RIO ~ O ~~ %O s
I S R Ra
~ . I
(II) (II
where X is selected from the group consisting of S, Se, and NH; R' and R2 are
selected from the group consisting of H and a protecting group; R3 is selected
from the group consisting of H and optionally substituted straight chain,
is branched, or cyclic, saturated or unsaturated hydrocarbon radicals and
their
protected derivatives; and R4, R5 and R6 are the same or different and are
selected from the group consisting of H, OH, SH, NH2, halogens and
constituents of compounds selected from the group consisting of
cyclopropanes, epoxides, aziridines and episulfides and their protected
2o derivatives. Preferably the cyclic sulfate is a 2,4-di-O-protected-D-or L-
erythritol-1,3-cyclic sulfate, such as 2,4-O-Benzylidene-D-or L-erythritol-1,3-
cyclic sulfate (i.e. R' and R2 comprise a benzylidene protecting group); R3 is
H
or a protected polyhydroxylated alkyl chain; and R4, R5 and R6 are selected
from the group consisting of OH and a protected OH group, such as
2s OCH2C6H5. The synthetic processes comprise the step of opening the cyclic
sulfate (II) by nucleophilic attack of the heteroatom X on the sugar (III).
In an alternative embodiment of the invention, the cyclic sulfate
(II) may be reacted with a 6-membered ring sugar having the general formula
30 (XI) to yield a compound having the general formula (X11):
-6-
SUBSTITUTE SHEET (RULE 26)

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R3 R ~~
4
Rz0 2
_3 O x
R~~ ~ O \ O R6
i ~S
s Rs Ra
O
(II) (XI)
(X11)
is where X is selected from the group consisting of S, Se and NH. In this
embodiment R~, R2, R3, R4, R5 and R6 are the same or different and are
selected from the group consisting of H, OH, SH, NH2, halogens and
constituents of compounds selected from the group consisting of
cyclopropanes, epoxides, aziridines and episulfides and R~ is selected from
2o the group consisting of H and optionally substituted straight chain,
branched,
or cyclic, saturated or unsaturated hydrocarbon radicals. Preferably R~, R2
and R3 are as described above in respect of compound (II) and R4, R5, R6 and
R' are selected from the group consisting of H, OH, SH, NH2, halogens and
constituents of compounds selected from the group consisting of
2s cyclopropanes, epoxides, aziridines and ~ episulfides and their protected
derivatives.
The application also relates to pharmaceutical compositions
comprising an effective amount of a compound according to formula (I) or
(X11) together with a pharmaceutically acceptable carrier and to methods of
so treating carbohydrate metabolic disorders, such as non-insulin dependent
diabetes, or different forms of cancer or Alzheimer's disease by administering
to a subject in need of such treatment an effective amount of such
compounds.
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Detailed Description of the Preferred Embodiments
Salacinol is a naturally occurring compound which may be
extracted from the roots and stems of Salacia reticulate, a plant native to
Sri
s Lanka and India. This application relates to synthetic routes for preparing
Salacinol (1), and its nitrogen (2) and selenium (3) analogues shown below.
OH
'~~~~\OH
to + X OS03 X=S (1)
HO X=NH (2)
HO~~, X=Se (3)
OH
This application also relates to synthetic routes for preparing the
is stereoisomers of compounds (1) to (3). Such analogues and stereoisomers
(including stereoisomers of Salacinol) comprise a new class of compounds
which are not naturally occurring and may find use as glycosidase inhibitors.
1.0 Summar~r of General Synthetic Scheme
Scheme 1 (a) below, shows the general synthetic scheme
developed by the inventors for arriving at the target compounds. To
synthesize different stereoisomers of Salacinol and its nitrogen and selenium
analogues (A) - (C), 5-membered-ring sugars are reacted with sulfate-
2s containing compounds in accordance with the invention (in Scheme 1 (a) the
letters (A), (B), and (C) represent all stereoisomers of Salacinol and its
nitrogen and selenium analogues (1), (2) and (3) respectively). The inventors
followed a disconnection approach for determining the preferred synthetic
route. A reasonable disconnection is one that gives the 5-membered-ring
3o sugars (D) since they can be synthesized easily from readily available
carbohydrate precursors. Nucleophilic substitution at C~ of the sulfate
fragment (E) can then yield the target molecules (Scheme 1 (a)). A potential
problem with this approach is that the leaving group (L) might act later as a
_g_
SUBSTITUTE SHEET (RULE 26)

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base to abstract the acidic hydrogens of the sulfonium salt and produce
unwanted products. Therefore, the cyclic sulfate (F) may be used instead of
(E) to obviate the problems associated with leaving group (L). Compound (G)
may similarly be used as a cyclic sulfate reagent and is a protected version
of
s (F).
HO
OH HO
X+ OsSO
HO ~~~ ~ RO + t 2 '
OH
HO OH RO OR L 03S0
X=S(A) (D) (E)
X=NH(B)
X=Se(C)
4
CsHs~O O HO 2 s O
O/'~~~ ~O ~ HO t O~~ ,O
i1 II
(G) O (F) O
Scheme 1 (a). Disconnection approach for the synthesis of (A) - (C)
(R=H, -CH2C6H5 and L= leaving group).
Scheme 1 (b) below shows generally the coupling reactions for
2o producing the target compounds (A) - (C).
R. R.
O6H5~0 O CsH5~0 p-
1 ~ 0'\Si O
Route 2 _ g
+ ~ ~o
RO ~ X
Ro X=S (A)
RO OR
R = H or benzyl ~ Route 1 RO OR X=NH (B)
Ho X=Se (C)
R'
OSOs'-
OH
OsSO
H2I
X+
HO ~ OH
R' = H
HO OH ' / ~ ~OH
R
OH
Scheme 1(b). Typical coupling reaction for the synthesis of different
3s stereoisomers (A) - (C)
-9-
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Route 1 of Scheme 1 (b) shows the general strategy of reacting a cyclic
sulfate
with a 5-membered ring sugar to produce an intermediate compound, which
may include benzyl or other protecting groups. As described in further detail
below, the intermediate compound is then deprotected to yield the target
s compounds. The inventors have determined that Route 2 of Scheme 1 (b), a
possible side reaction, does not occur.
2.0 Synthesis of Reaqents
to
Cyclic sulfates and 5-membered-ring sugars were prepared in
accordance with the synthetic schemes described below. As will be apparent
to a person skilled in the art, other equivalent schemes for producing the
reagents of the invention could be substituted.
Is
2.1 Cyclic sulfates
Cyclic sulfates were prepared in analogous fashion to the
ethylidene acetal.$ The cyclic sulfate (7) was synthesized in 4 steps starting
2o from D-glucose (Scheme 2). 2,4-O-Benzylidene-D-erythrithol (5) was
synthesized from D-glucose in two steps,9~~° and then treated with
thionyl
chloride to yield the cyclic sulfite (6) which was oxidized to the cyclic
sulfate
(7) as described by Calvo-Flores et a1.$
2s OH 4 4
C6H5~0 2 3 C6H5~0
O
HO O PhCHO,HF O HO OH 1.~ O 3 OH
HO OH
OH 2.NaBH4 OH
HO (4) 64% (5) 48°/
SOCIz
4
~O 2 NaI04, RuCl3
3O C6H5 3 O ~- C6H5~0 z s
O i O ~ /O O O
~S/ ~O
(7) 95% O (()) 82%
Scheme 2. Synthesis of the cyclic sulfate (7).
- to -
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The enantiomer (10) was also synthesized using the same route
but starting from L-glucose (Scheme 3).
HO CsH5~0 HO C6H5~0 OH
HO/~=~~~~H phCHO,H~~ O O OH 1. NaI04 ~ O~H
HO O OH OH 2. N B
51% (8) 59%
SOCIZ
CH~
CsHs O O NaI~ OA,RuCl3 s s O O O .
S O 'SAO
O
(9) 60%
(10) 86%
Scheme 3. Synthesis of the cyclic sulfate (10).
2 2 Synthesis of 5-Membered-ring Heterocycles
is In order to synthesize one of the 5-membered-ring sugars (D,
X=S), 1,4-anhydro-3-O-benzyl-4-thio-D-arabinitol (11), was synthesized in 9
steps starting from D-glucose (Scheme 4).~~ Benzylation of the compound
(11), using benzyl bromide in DMF yielded 1,4-anhydro-2,3,5-tri-O-benzyl-4
thio-D-arabinitol (12) in 90% yield. Compound (11) was debenzylated to give
1,4-anhydro-4-thio-D-arabinitol (13) in 97% yield using a Birch reduction.
0
OH O ~O HO
HO "i~ O _
O OH Acetone,ZnCl= pH NaH,BnBr O 1.HC1 Ogn
HO - ~ O THP,D~ OBn
HO O 2. NaI04 p
O ~ O ~ 3. NaBHø O
60% 99% 66%
HCl/MeOH
HO
HO Ms0 O
S 1.HC1 Bn0 S'O OMe~ OB OMeE MsC1 Ogn OMe
HO ~ Pyridine
2.NaBH4 OH
OBn ° OMs 90%
(11) ss°/
1. NaH Na, NH3
2. BnBr
Bn0 HO
S S
Bn0 HO Bn=CHzPh
Ms= CH3S Oz
OBn OH
(12) 90% (13) 9~%
Scheme 4. Synthesis of compounds (11) - (13).
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Scheme 4. Synthesis of compounds (11) - (13).
The L-isomer, 1,4-anhydro-2,3,5-tri-O-benzyl-4-thio-L-arabinitol
(14) was synthesized in 5 steps starting from D-xylose (Scheme 5).~2
HO HO Bn0 Bn0
O OH O OMe O OH
OH MeOH, HC1 OH 1. BnBr ~ Ogn OH 1.H+ OH
2. A~ ~ OBn
2.NaBH 4
OH OH
55% OBn 81% OBn
~MeSO ZCI
Bn0 Bn0
OMs N3 OMs pMs
OH H2,Pd/C OBn ' NaN3 OBn
OH OBn
HO (16) 90% 65% OBn (15) 97%
Se NaZSe ~ Na25
OBn
I S
BnO OBn OBn
(17)
Bn0 OBn
(14) 86%
Scheme 5. Synthesis of compounds (14)-(17)
1,4-Di-O-methanesulfonyl-2,3,5-tri-O-benzyl-D-xylitol (15) is also
a key intermediate for the synthesis of the aza and selena sugars (16) and
to (17). 1,4-Dideoxy-1,4-imino-L-arabinitol (16)3 was synthesized in 7 steps
starting from D-xylose (Scheme 5). The enantiomer (19)'3 was synthesized in
an analogous way starting from L-xylose (Scheme 6). Compound (19) was
also synthesized in 10 steps starting from D-xylose.~3 1,4-Anhydro-2,3,5-tri-
O-benzyl-4-seleno-D-arabinitol (20) was synthesized in 5 steps starting from
is L-xylose (Scheme 6). To synthesize compound (20), Na2Se was made in-situ
by treatment of selenium metal with sodium in liquid ammonia.
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O OH O OMe O OH
O MeOH, H_CI O 1. BnBr OH + OH
2. A~ c0~ 0 n 1.H O n
2.
OH
HO HO OH Bn0 OBn Bn0 Ogn
84% 77%
MeSO2C1
HO H
I
OMs N3 OMs OMs
O H2, Pd/C n ~ N~3 O n
OH Bn0 OBn Bn0 Ogn
(19) 90% 82% (18) 93%
Bn0 Na~Se
Se
O n
OBn
(20) 80%
Scheme 6. Synthesis of compounds (19) and (20).
Scheme 6(a) below shows a more generalized scheme for
s synthesizing compound (20) using other possible protecting groups (R =COR,
CH2C6H4-OMep).
OH 0 OMe 0 OH
0 MeOH, HCI p I. RX OH LH+ OH
>~ ~ T> ~ -=~ O
2. H 2.NaBH q
OH
HO HO OH RO OR RO OR
84% 77%
MeSO2C1
HO H
I
OMs N3 OMs OMs
0 H2, Pd/C E NaN3 O
OH RO OR RO OR
(19) 90% g2% (18) 93%
RO Na2Se
Se
0
OR
(20) 80%
Scheme 6(a). Synthesis of compounds (19) and (20). (R = COR,
io CH2C6H4-OMep).
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3.0 S nthesis of the Target Compounds
The target compounds (1) - (3) were prepared by opening of the
s cyclic sulfates by nucleophilic attack of the heteroatoms on the 5-membered
rings (Scheme 1 (b) above). The heteroatom gives rise to a positively charged
cation and the cyclic sulfate gives rise to a negatively charged counterion.
This internal salt structure may explain the stability of the target compounds
toward decomposition by further nucleophilic attack.
to
3.1 Synthesis of Salacinol
Salacinol (1) was synthesized by nucleophilic substitution of the
protected thio-arabinitol (12) with the cyclic sulfate (10) (1.2 equiv) in dry
is acetone containing K2C03, to give the protected intermediate compound (21)
in 33% yield. Hydrogenolysis of the benzyl and benzylidene groups in
AcOH:H20, 4:1 afforded Salacinol (1) in 67% yield (Scheme 7).
C6H5
O~O OH
~'~~~OH
+ S OSO3 + $ OSO3
BnO~\~ C6H5 O~~~S O BnO~I~ HzPdlC I-10~'~ _
AcOH
Bn0 OBn O BnO~ OBn HO~ OH
(12) (10) (21) Salacinol (1)
Scheme 7. Synthesis of Salacinol (1)
The same procedure was used to prepare intermediate
compound (22) in 79% yield from the enantiomeric cyclic sulfate (7).
2s Deprotection as before gave compound (23) in 59% yield (Scheme 8).
Compound (23) is a diastereomer of Salacinol (1).
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C6H5
O~O OH
!~OH
-1- S OSOg + S OSOg
Bn0 '' CsHs p~=S,O 8~~,\~ Hz~ ~,~
Bn0 OBn n Bn0 OBn AcOH HO OH
O
(12) (7) (22) (23)
Scheme 8. Synthesis of compound (23)
s Compound (24) was prepared in 40% yield from (7) and the
enantiomeric thio-ether (14) (Scheme 9). Deprotection in 80% yield gave the
enantiomer of Salacinol (25).
CsHs
_O~O OH
~OH
+ OSO
Bn0 /~~ S CsH5~0 O Bn0'~~.. + S OS03 HO ~~.. S -
+ O' ~ ~ ~~O ~ Hz,Pd/C
w
Bn0 'OBn S Bn0 'OBn AcOH HO 'OH
O
(14) (7) (24) (25)
to Scheme 9. Synthesis of compound (25)
To reduce the number of synthetic steps, the inventors
attempted the coupling reactions with the deprotected thin-arabinitols. Thus,
the partially deprotected compound (11) was reacted with the cyclic sulfate
is (10) in acetone, to give compound (26) in 32% yield. Deprotection yielded
Salacinol (1) in 36% yield (Scheme 10).
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CsHs
O~O OH
y'~~OH
S + S OSO3 + S OS03
HO \ C6H5 o~~~s ~~'1~ g2Pd/C HO~1'
Bn0 OH O BnO~ OH A°~ HO~~ OH
(11) (10) (26) Salacinol (1)
Scheme 10. Synthesis of Salacinol (1)
s The fully-deprotected thio-arabinitol (13) was not soluble in
acetone and the reaction in methanol produced several products.
3.2 Synthesis of Selenium Analogues
to The seleno-analogue intermediate (27) (R=CH2C6H5) was made
starting from the seleno-arabinitol (20) (R=CH2C6H5) and the cyclic sulfate
(10) in excellent yield 86% (Scheme 11 ), but NMR spectroscopy showed the
presence of two isomers in a ratio of 7:1 that differed in stereochemistry at
the
stereogenic selenium center. The isomers were separable by analytical
is HPLC. The inventors have assigned the name "Blintol" to the new selenium
analogue (3).
CsHs
O~O OH
~'~~~OH
Se + Se OS03 +Se OS03
RO~~ CgHS~~~~ ,O RO~ HO~~ _
+ O S ~
RO OR O RO OR HO OH
( 20 ) ( 10 ) ( 27 ) Blintol ( 3 )
R = H, COR, CH2C6H5, CH2C6H4-OMep
Scheme 11. Synthesis of Blintol (3)
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The seleno-analogue intermediate (28) (R=CH2C6H5) was made
starting from the seleno-arabinitol (20) (R=CH2C6H5) and the cyclic sulfate
(7)
in excellent yield 97% (Scheme 12); a mixture of two isomers in a ratio of 3:1
that differed in stereochemistry at the stereogenic selenium center was
s obtained. The isomers were separable by analytical HPLC.
C6H5
O~O O H
~OH
Se C6H5~0 + Se OS03 +Se OS03
RO O
+ O~~ .O ~--~,
RO~ OR a RO~ OR HO~ OH
O
(20) (7) (28) (29)
R = H, COR, CH2C5H5, CH2C6H4-OMep
Scheme 12. Synthesis of compound (29)
io
Compound (29) is a diastereomer of Blintol (3).
3.3 Synthesis of Nitrogen Analogues
is The nitrogen analogue intermediate (30) was made by the
reaction of the deprotected imino-arabinitol (19) with the cyclic sulfate (10)
in
a good yield 72% (Scheme 13). Compound (19) was not soluble in acetone
so the reaction v~ias performed in dry methanol. A side product (19%) which
was identified to be the product of methanolysis of the cyclic sulfate was
20 obtained. The inventors have assigned the name "Ghavamiol" to the new
nitrogen analogue (2). Compound (30) was deprotected to give Ghavamiol
(2) in 64% yield.
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C6H5
O~O OH
H, ~~ '\I H. ~' '\'0H
+ N OS03 + N OS03
HO \ C6H5 ~p~~~s ~~11~ HZ,pd/C _HO~,'~~
HO~ OH + O HO\'~OH AcOH HO~ OH
(19) (10) (30) Ghavamiol (2)
Scheme 13. Synthesis of Ghavamiol (2)
s The enantiomer intermediate (31) was made by the reaction of
the deprotected imino-arabinitol (16) with the cyclic sulfate (7) in a good
yield
72% (Scheme 14). A side product (21 %) which was identified to be the
product of methanolysis of the cyclic sulfate was obtained. Compound (31)
was deprotected to give compound (32) in 77% yield. Compound (32) is the
to enantiomer of Ghavamiol (2).
C6H5
O~O OH
H H ~ H ~OH
+~ OSO +
HO ~~ N C6H5~~0 HO ~~,. N -3 HO ~~.. N OS03
+ 0 O_~ .,O -~ ~ HZ,Pd/C
HO 'pH S HO OOH AcOH HO OH
O
(~) (
Scheme 14. Synthesis of compound (32)
4.0 Alternative Synthetic Scheme
In an alternative embodiment of the invention, target compounds
having potential application as glycosidase inhibitors may be synthesized in
2o the manner described above using 6-membered rather than 5-membered ring
heterocycles as reagents. As in the embodiments described above, the cyclic
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sulfate (described above) is opened in the coupling reaction due to
nucleophilic attack of the heteroatoms (i.e. X=S, Se, N) on the ring sugars.
As
will be apparent to a person skilled in the art, the general formulas for the
6-
membered sugar reagent and resulting target compound are as shown below.
Rs Rs
R~
Ra
-R~
+ OS03
X
Rs R3
Rs Ra RZ R1
The 6-membered ring target compound shares the same internal salt
structure as the 5-membered ring embodiment. The substituent groups may
vary as described above without departing from the invention.
is
5.0 Examples
The following examples will further illustrate the invention in
greater detail although it will be appreciated that the invention is not
limited to
2o the specific examples.
5.1 Experimental Methods
Optical rotations were measured at 20° C. ~ H and ~3C NMR
2s spectra were recorded at 400.13 and 100.6 MHz for proton and carbon
respectively. All assignments were confirmed with the aid of two-dimensional
~H,~H (COSYDFTP) or ~H,~3C (INVBTP) experiments using standard Broker
pulse programs. MALDI-TOF mass spectra were obtained for samples
dispersed in a 2,5-dihydroxybenzoic acid matrix using a Perseptive
3o Biosystems Voyager-DE instrument. Silica gel for chromatography was
Merck kieselgel 60. High resolution mass spectra were LSIMS (Fab), run on
a Kratos Concept H double focussing mass spectrometer at 10000 RP.
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5.2 Preparation of Intermediates
2 1 Example 1 - Preparation of Cyclic Sulfate (7) (Scheme 2)
s Step 1- 2,4-O-Benzylidene-D-erythritol (5).
Compound (5) was prepared from 4,6-O-benzylidene-D-glucose (4) according
to standard procedures.9~~° Compound (5) has been mentioned by
MacDonald et al.,~° without characterization, which is therefore
dealt with
here. Mp 138-139°C ; [a]p -44° (c 1.0, MeOH) ; ~H NMR (CD30D): 8
7.53-
io 7.28 (5H, m, Ar), 5.53 (1 H, s, H-5), 4.2 (1 H, dd, J = 10.1, 3.6 Hz, H-
4a), 3.92
(1 H, dd, J = 12.1, 1.7 Hz, H-1 a), 3.74 (1 H, dd, J = 12.1, 5.7 Hz, H-1 b),
3.67-
3.55 (3H, m, H-3, H-2, H-4b); ~3C NMR (100.6 MHz, CD30D): b 139.52 (C;pso),
129.77 (Cpara), 128.99, 127.49 (4Cortt,o+meta), 102.36 (C-5), 84.22 (C-3),
72.21
(C-4), 62.76 (C-1 ), 62.59 (C-2); MALDI-TOF MS: m/e 211 (M+ + H), 233 (M+ +
is Na). Anal. Calcd for C~~H~4O4: C, 62.83; H, 6.72. Found: C, 62.96; H, 6.55.
Step 2 - 2,4-O-Benzylidene-D-erythritol-1,3-cyclic sulfite (6).
A solution of the diol (5) (4.5g, 21 mmol) and Et3N (11 mL, 4equiv) in dry
CH2C12 (90mL) was added dropwise to a solution of SOC12 (2.4mL, 1.5equiv)
in dry CH2C12 (60mL), with stirring in an ice-bath under an N2 atmosphere.
2o Stirring was continued at 0°C, until TLC (hex:EtOAc, 4:1) showed
complete
disappearance of the starting material. The mixture was diluted with CH2C12
(150mL) and washed with H20 (150mL) and brine (150mL). The organic
solution was dried (NaZS04) and concentrated on a rotary evaporator. The
product was purified by flash chromatography [hex:EtOAc, 4:1 + 0.1 % Et3N] to
2s give a mixture of two diastereomers (4.5g, 82%). One of the isomers was
selectively recrystallized from EtOAc:hex. Mp 137-139°C ; [a]o
+32° (c 1.0,
CH2C12) ; ~ H NMR (CD2C12): 8 7.48-7.36 (5H, m, Ar), 5.68 (1 H, s, H-5), 5.04
(1 H, ddd, J = 10.4, 9.5, 5.0 Hz, H-3), 4.80 (1 H, dd, J = 10.4, 10.4 Hz, H-1
a),
4.24 (1 H, dd, J = 10.5,5.0 Hz, H-4e), 4.18 (1 H, ddd, J = 10.4, 9.5, 4.8 Hz,
H-
30 2), 4.06 (1 H, dd, J = 10.4, 4.8 Hz, H-1 e), 3.89 (1 H, dd, J = 10.5,10.4
Hz, H-
4a); ~3C NMR (100.6 MHz, CD2C12): 8 137.14 (C;Pso), 129.74 (Cpara), 128:65,
126.50 (4Cortho+meta), 102.72 (C-5), 73.56 (C-2), 68.16 (C-4), 63.90 (C-3),
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60.18 (C-1). Anal. Calcd for C~~H~2O5S: C, 51.55; H, 4.72. Found: C, 51.80;
H, 4.66.
Step 3 - 2,4-O-Benzylidene-D-erythritol-1,3-cyclic sulfate (7).
s The cyclic sulfite (6) (3.5g, 14mmol) was dissolved in a mixture of MeCN
(50mL) and CC14 (50mL), and NalO4 (4.1g, 1.5equiv) and RuCl3~H~0 (50mg)
were added followed by H20 (50mL). The mixture was stirred vigorously at rt
until TLC (hex:EtOAc,4:1) showed complete disappearance of the starting
material. The mixture was diluted with Et20 (200mL) and washed with H20
to (200mL) and brine (200mL). The organic solution was dried (Na2S04) and
concentrated on a rotary evaporator. The product was purified by flash
chromatography [hex:EtOAc, 4:1 + 0.1% Et3N] fio yield a white solid (3.5g,
95%). A portion of the product was recrystallized from EtOAc:hex. Mp 115-
125°C (dec); [a]p +4° (c 1.0, CHC13) ; ~ H NMR (CD2C12): b 7.48-
7.37 (5H, m,
is Ar), 5.65 (1 H, s, H-5), 4.86 (1 H, ddd, J = 10.2, 9.8, 5.0 Hz, H-3), 4.76
(1 H, dd,
J = 10.7, 10.5 Hz, H-1 a), 4.65 (1 H, dd, J = 10.5,5.0 Hz, H-1 e), 4.44 (1 H,
dd, J
= 10.5, 5.0 Hz, H-4e), 4.25 (1 H, ddd, J = 10.7, 9.8, 5.0 Hz, H-2), 3.97 (1 H,
dd,
J = 10.5,10.2 Hz, H-4a); '3C NMR (100.6 MHz, CD2C12): 8 136.32
(C;pS°),
130.03 (Cpara)~ 128.74, 126.52 (4C°~t,o+meta), 102.98 (C-5), 75.74 (C-
3), 73.19
20 (C-1 ), 71.68 (C-2), 67.64 (C-4); MALDI-TOF MS: m/e 273 (M+ + H), Anal.
Calcd for C~~H~~O6S: C, 48.52; H, 4.45. Found: C, 48.43; H, 4.39.
2 2 Example 2 - Preparation of thio-arabinitol (Scheme 4)
2s 1,4-Anhydro-2,3,5-tri-O-benzyl-4-thio-D-arabinitol(12).
A mixture of 1,4-anhydro-3-O-benzyl-4-thio-D-arabinitol (1.0g, 4.2mmol) and
60% NaH (0.85g, 5equiv) in DMF (20mL) was stirred in an ice-bath for 1 h. A
solution of benzyl bromide (1.9mL, 3.8equiv) in DMF (5mL) was added and
the solution was stirred at rt for 3h. The mixture was added to ice-water
30 (150mL) and extracted with Et20 (150mL). The organic solution was dried
(Na2S04) and concentrated. The product was purified by flash
chromatography [hex:EtOAc, 4:1] to give a syrup (1.6g, 90%). [a]p +5°
(c 1.6,
CHCI3) ; ~ H NMR (CDCI3): 8 7.38-7.23 (15H, m, Ar), 4.64-4.45 (6H, m,
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CHC13) ; ~H NMR (CDC13): 8 7.38-7.23 (15H, m, Ar), 4.64-4.45 (6H, m,
CH2Ph), 4.19 (1 H, dd, J = 8.9, 4.6 Hz, H-2), 4.11 (1 H, dd, J = 7.2, 3.8 Hz,
H-
3), 3.69 (1 H, dd, J = 8.8, 7.6 Hz, H-5a), 3.57 (1 H, ddd, J = 7.5, 6.4, 3.6
Hz, H-
4), 3.50 (1 H, dd, J = 8.9, 6.3 Hz, H-5b), 3.08 (1 H, dd, J = 11.4, 5.1 Hz, H-
1 a),
s 2.91 (1 H, dd, J = 11.4, 4.6 Hz, H-1 b). '3C NMR (100.6 MHz, CDC13): 8
138.16,138.06,137.88 (3C;pso), 128.40-127.59 (15CAr), 85.08 (C-3), 85.04 (C-
2), 73.01 (CH2Ph), 72.34 (C-5), 71 .85,71.50(2CH2Ph), 48.99 (C-4), 33.10 (C-
1 ). Anal. Calcd for C2gH28~3s. C, 74.25; H, 6.72. Found: C, 74.18; H, 6.53.
io 5.2.3 Example 3 - Preparation of seleno-arabinitol (Scheme 6)
1,4-Anhydro-2,3,5-tri-O-benzyl-4-seleno-D-arabinitol (20).
Selenium metal (1.1g, 14mmol) was added to liquid NH3 (60mL) in a -
50°C
bath and small pieces of Na (0.71 g) were added until a blue color appeared.
is A small portion of selenium (20mg) was added to remove the blue color. NH3
was removed by warming on a water bath and DMF was added and removed
under high vacuum to remove the rest of NH3. A solution of the mesylated
compound (18) (7.4g, 12.7mmol) in DMF (100mL) was added and the mixture
was stirred under N2 in a 70°C bath for 3 h. The mixture was cooled and
the
2o solvent was removed on high vacuum. The product was partitioned between
CH2C12 (150mL) and water (50mL), and the organic solution was washed with
water (50mL) and brine (50mL) and dried (MgSO4). The product was purified
by flash chromatography (hex:EtOAc, 3:1) to give a yellow oil (4.74g, 80%).
[a]p +22° (c 1.3, CHC13); ~H NMR (CDC13): 8 7.22-7.48 (15H, m, Ar),
4.67,
2s 4.61 (2H, 2d, J = 11.8 Hz, CH2Ph), 4.56, 4.48 (2H, 2d, J = 12.1 Hz,CH2Ph),
4.53, 4.50 (2H, 2d, CHZPh), 4.22 (1 H, dd, J = 10.1, 5.1 Hz, H-2), 4.07 (1 H,
dd,
J = 4.6, 4.6 Hz, H-3), 3.85 (1 H, dd, J = 9.2, 7.6 Hz, H-5a), 3.77 (1 H, ddd,
J =
7.5, 6.9, 4.5 Hz, H-4), 3.53 (1 H, dd, J = 9.1, 6.8 Hz, H-5b), 3.11 (1 H, dd,
J =
10.4, 5.1 Hz, H-1 a), 2.96 (1 H, dd, J = 10.4, 5.3 Hz, H-1 b). ~3C NMR (100.6
30 MHz, CDC13): 8 138.24,138.21,138.06 (3C;pso), 128.40-127.60 (15CAr), 85.93
(C-2), 85.63 (C-3), 72.96 (C-5, CH2Ph), 72.14,71.50(2CH2Ph), 42.59 (C-4),
23.96 (C-1 ). Anal. Calcd for C26H2803Se: C, 66.65; H, 6.03. Found: C, 66.49;
H, 6.05.
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5.2.4 Example 4 - General procedure for the synthesis of the protected
sulfonium, selenonium and ammonium sulfates (21), (22), (24), (26), (27),
X28). (30), (31 ) (Schemes 7 - 14).
The thio, aza or selenosugar (3mmol) and the cyclic sulfate (1.2equiv) were
dissolved in dry acetone (in the case of (21), (22), (24), (26), (27) and
(28)) or
dry methanol (in the case of (30) and (31)) (0.5mL) and anhydrous K2C03
(7mg) was added. The mixture was stirred in a Caries tube in an oil-bath
io (75°C) overnight. The solvent was removed under reduced pressure and
the
product was purified by column chromatography.
1-((1',4'-Anhydro-2',3',5'-tri-O-benzyl-4'-thio-D-arabinitol)-4'-S-yl)-2,4-O-
benzylidene-1-deoxy-L-erythritol-3-sulfate (21).
Is Column chromatography [CHCI3:MeOH, 10:1 + 0.1% Et3N] of the crude
product gave an amorphous solid (33%). [a]p -11.9° (c 1.7, CH2C12) ; 'H
NMR (CD2C12): 8 7.49-7.12 (20H, m, Ar), 5.54 (1 H, s, H-5), 4.59 (1 H, ddd, J
=
9.9, 5.4, 4.5 Hz, H-3), 4.55-4.33 (8H, m, 4CH2Ph, H-2', H-4a, H-1 a, H-3'),
4.29
(1 H, dt, J = 9.5, 3.0 Hz, H-2), 4.25 and 4.15 (2H, 2d, J = 11.9 Hz, CH2Ph),
20 4.04 (1 H, m, H-1'a) 4.02-3.95 (2H, m, H-4', H-1 b), 3.78 (1 H, dd, J =
10.7, 10.7
Hz, H-4b), 3.74 (1 H, dd, J = 13.6, 3.8 Hz, H-1'b), 3.62 (1 H, dd, J = 9.9,
8.6 Hz,
H-5'a), 3.54 (1 H, dd, J = 9.9, 7.2 Hz, H-5'b); ~3C NMR (100.6 MHz, CD2C12): 8
137.34,137.24,136.56,136.39 (4C;ps°), 129.73-126.62 (20CA~), 101.95 (C-
5),
83.75 (C-3'), 82.82 (C-2'), 76.80 (C-2), 73.73,72.84, 72.52 (3CH2Ph),
2s 69.54.(C-4), 67.01 (C-5'), 66.48 (C-3), 65.27 (C-4'), 49.67 (C-1), 48.28 (C-
1');
MALDI-TOF MS: m/e 693 (M+ + H). Anal. Calcd for C37H4pOgS2: C, 64.14; H,
5.82. Found: C, 63.88; H, 5.83.
1-((1',4'-Anhydro-2',3',5'-tri-O-benzyl-4'-thio-D-arabinitol)-4'-S-yl)-2,4-O-
benzylidene-1-deoxy-D-erythritol-3-sulfate (22).
3o Column chromatography [CHCI3:MeOH, 10:1 + 0.1 % Et3N] of the crude
product gave an amorphous solid (79%). [a]p -46.9° (c 0.65, CHZC12); ~H
NMR (CD2C12): 8 7.43-7.10 (20H, m, Ar), 5.49 (1 H, s, H-5), 4.62-4.34 (11 H,
m,
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SUBSTITUTE SHEET (RULE 26)

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CH2Ph, H-3, H-4a, H-2', H-1 a, H-3'), 4.30-4.21 (2H, m, H-2, H-4'), 3.96 (1 H,
dd, J = 9.7, 6.2 Hz, H-5'a), 3.90 (1 H, dd, J = 13.3, 3.4 Hz, H-1 b), 3.82 (1
H, dd,
J = 9.8, 9.8 Hz, H-5'b), 3.79-3.71 (2H, m, H-1'a, H-4b), 3.51 (1 H, dd, J =
13.2,
3.9 Hz, H-1'b); ~3C NMR (100.6 MHz, CD2C12): 8
137.62,137.27,136.48,136.29 (4C;ps°), 129.80-126.56 (20CA~), 102.16 (C-
5),
84.25 (C-3'), 82.56 (C-2'), 77.07 (C-2), 74.02,72.74 (3CH2Ph), 69.75 (C-4),
67.19 (C-5'), 66:82 (C-3), 65.76 (C-4'), 50.41 (C-1 ), 49.60 (C-1'); MALDI-TOF
MS: m/e 693 (M+ + H). Anal. Calcd for C37H4oO9S2: C, 64.14; H, 5.82. Found:
C, 64.16; H, 5.73.
to
1-((1',4'-Anhydro-2',3',5'-tri-O-benzyl-4'-thio-L-arabinitol)-4'-S-yl)-2,4-O-
benzylidene-1-deoxy-D-erythritol-3-sulfate (24).
Column chromatography [CHCI3:MeOH, 10:1 + 0.1% Et3N] of the crude
product gave an amorphous solid (40%). [a]o +14.3° (c 1.4, CH2C12) ; '
H
is NMR (CD~C12): 8 7.49-7.12 (20H, m, Ar), 5.55 (1 H, s, H-5), 4.60 (1 H, ddd,
J =
9.8, 5.5, 4.5 Hz, H-3), 4.55-4.44 (5H, m, 3CH2Ph, H-2', H-4a), 4.42 (1 H, dd,
J
= 13.3, 2.3 Hz, H-1 a), 4.39-4.34 (2H, m, CH2Ph, H-3'), 4.28 (1 H, dt, J =
9.8,
2.9 Hz , H-2), 4.24 and 4.14 (2H, 2d, J = 11.9 Hz, CH2Ph), 4.10 (1 H, d, J =
13.4 Hz H-1'a), 3.98-3.90 (2H, m, H-4', H-1 b), 3.78 (1 H, dd, J = 10.5, 10.5
Hz,
2o H-4b), 3.67 (1 H, dd, J = 13.4, 3.8 Hz, H-1'b), 3.62 (1 H, dd, J = 9.9, 8.7
Hz, H
5'a), 3.53 (1 H, dd, J = 9.9, 7.2 Hz, H-5'b); ~3C NMR (100.6 MHz, CD2C12): 8
137.32,137.26,136.48,136.25 (4C;ps°), 129.79-126.64 (20CA~), 102.06 (C-
5),
83.96 (C-3'), 82.74 (C-2'), 76.93 (C-2), 73.81, 72.97,72.57 (3CH2Ph),
69.59.(C-4), 67.07 (C-5'), 66.36 (C-3), 66.31 (C-4'), 49.96 (C-1), 48.52 (C-
1').
2s Anal. Calcd for C37H4pOgS~: C, 64.14; H, 5.82. Found: C, 64.13; H, 5.74.
1-((1',4'-Anhydro-3'-O-benzyl-4'-thio-D-arabinitol)-4'-S-yl)-2,4-O-
benzylidene-1-deoxy-L-erythritol-3-sulfate (26).
Column chromatography [CHCI3:MeOH, 10:1 + 0.1 % Et3N] of the crude
so product gave an amorphous solid (32%).; ~H NMR (CD2C12): 8 7.49-7.26
(10H, m, Ar), 6.22 (1 H, d, J = 4.4 Hz, 2'-OH), 5.54 (1 H, s, H-5), 4.96 (1 H,
br-s,
H-2'), 4.64 (1 H, d, J = 11.6 Hz, CH2Ph), 4.64-4.62 (1 H, m, 5'-OH), 4.56 (1
H,
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SUBSTITUTE SHEET (RULE 26)

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d, J = 11.6 Hz, CH2Ph), 4.54-4.48 (1 H, m, H-3), 4.46 (1 H, dd, J = 10.5, 5.4
Hz,
H-4a), 4.33-4.25 (3H, m, H-3', H-2, H-1'a), 4.12 (1 H, dd, J = 13.5, 2.6 Hz, H-
1 a), 4.12-4.09 (1 H, m, H-4'), 4.01 (1 H, dd, J = 13.5, 3.4 Hz, H-1 b), 3.92-
3.82
(2H, m, H-5'a, H-5'b), 3.78 (1 H, dd, J = 10.5, 10.1 Hz, H-4b), 3.67 (1 H, dd,
J =
s 13.5, 3.9 Hz, H-1'b); ~3C NMR (100.6 MHz, CD2C12): 8 136.92,136.73
(2C;ps°),
129.97-126.61 (10CA~), 102.32 (C-5), 88.45 (C-3'), 76.61 (C-2), 76.22 (C-2'),
72.96 (CH2Ph), 71.24 (C-4'), 69.27 (C-4), 66.96 (C-3), 60.51 (C-5'), 52.43 (C-
1'), 48.30 (C-1 ); MALDI-TOF MS: m/e 513 (M+ + H). Anal. Calcd for
C23H28O9S2: C, 53.89; H, 5.51. Found: C, 53.64; H, 5.34.
io
1-((1',4'-Anhydro-2',3',5'-tri-O-benzyl-4'-seleno-D-arabinitol)-4'-Se-yl)-2,4-
O-benzylidene-1-deoxy-L-erythritol-3-sulfate (27).
Column chromatography [CHC13 :MeOH , 15:1] of the crude product gave an
amorphous solid (86%). NMR showed the presence of two isomers (7:1) at
is the stereogenic selenium center which were separated on analytical HPLC
[acetonitrile/H20]. Anal. Calcd for C3~H4oO9SSe: C, 59.99; H, 5.45. Found: C,
59.91; H, 5.44.
1-((1',4'-Anhydro-2',3',5'-tri-O-benzyl-4'-seleno-D-arabinitol)-4'-Se-yl)-2,4-
2o O-benzylidene-1-deoxy-D-erythritol-3-sulfate (28).
Column chromatography [CHC13 :MeOH , 15:1] of the crude product gave an
amorphous solid (96%). NMR showed the presence of two isomers (3:1) at
the stereogenic selenium center which were separated on analytical HPLC
[acetonitrilelH20]. Anal. Calcd for C37H4oO9SSe: C, 59.99; H, 5.45. Found: C,
2s 59.91; H, 5.37.
1-((1',4'-Dideoxy-1',4'-imino-D-arabinitol)-4'-N-yl)-2,4-O-benzylidene-1-
deoxy-L-erythritol-3-sulfate (30).
A mixture of 1,4-Dideoxy-1,4-imino-D-arabinitol (19) (100mg, 0.7mmol) and
30 2,4-O-benzylidene-L-erythritol-1,3-cyclic sulfate (10) (235mg, 1.2equiv)
were
dissolved in dry MeOH (0.5mL) and anhydrous K2C03 (15mg) was added.
The mixture was stirred in a Caries tube in an oil-bath (75°C)
overnight. The
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SUBSTITUTE SHEET (RULE 26)

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solvent was removed under reduced pressure and column chromatography
[CH2C12:MeOH, 4.5:1] of the crude product gave an amorphous solid (219mg,
72%). ' H NMR (CD30D): ~ 7.53-7.30 (5H, m, Ar), 5.61 (1 H, s, H-5), 4.53 (1 H,
dd, J = 11.1, 5.2 Hz, H-4a), 4.25 (1 H, m, H-2), 4.20 (1 H, ddd, J = 9.8, 5.2,
4.4
s Hz, H-3), 4.11 (1 H, br-s, H-2'), 3.99-3.84 (4H, m, H-1 a, H-3', H-5'a, H-
5'b),
3.82 (1 H, dd, J = 10.7, 9.8 Hz H-4b) 3.58 (1 H, m, H-1'a), 3.55-3.42 (2H, m,
H-
1'b, H-4'), 3.38 (1 H, m, H-1 b); ~3C NMR (100.6 MHz, CD30D): 8 138.72
(C;pso), 130.12 (Cpara)~ 129.21, 127.39 (4Cortho+meta)~ 102.33 (C-5), 78.01 (C-
4',
C-3', C-2), 76.31 (C-2'), 70.29 (C-4), 69.02 (C-3), 62.64 (C-1'), 60.51 (C-
5'),
l0 58.46 (C-1); MALDI-TOF MS: m/e 428 (M+ + Na) ,406 (M+ + H); HRMS. Calcd
for C~gH23OgSN (M + H): 406.1179. Found: 406.1192.
1-((1',4'-Dideoxy-1',4'-imino-L-arabinitol)-4'-N-yl)-2,4-O-benzylidene-1-
deoxy-D-erythritol-3-sulfiate (31).
Is A mixture of 1,4-Dideoxy-1,4-imino-L-arabinitol (16) (80mg, 0.6mmol) and
2,4-
O-benzylidene-D-erythritol-1,3-cyclic sulfate (7) (190mg, 1.2equiv) were
dissolved in dry MeOH (0.5mL) and anhydrous K2C03 (10mg) was added.
The mixture was stirred in a Caries tube in an oil-bath (75°C)
overnight. The
solvent was removed under reduced pressure and column chromatography
20 [CH2C12:MeOH, 5:1] of the crude product gave an amorphous solid (175mg,
72%). ~ H NMR (CD30D): b 7.52-7.31 (5H, m, Ar), 5.62 (1 H, s, H-5), 4.53 (1 H,
dd, J = 10.9, 5.2 Hz, H-4a), 4.28 (1 H, m, H-2), 4.20 (1 H, ddd, J = 9.7, 5.1,
4.6
Hz, H-3), 4.14 (1 H, br-s, H-2'), 4.03 (1 H, m, H-1 a), 3.98-3.84 (3H, m, H-
3', H-
5'a, H-5'b), 3.81 (1 H, dd, J = 10.9, 10 Hz H-4b) 3.63 (1 H, m, H-1'a), 3.55-
3.42
2s (2H, m, H-1'b, H-4'), 3.38 (1 H, m, H-1 b); ~3C NMR (100.6 MHz, CD30D): 8
138.66 (C;pSO), 130.15 (Cpara), 129.23, 127.40 (4Cor~ho+meta)~ 102.34 (C-5),
77.81 (C-4'), 77.52 (C-3', C-2), 76.19 (C-2'), 70.27 (C-4), 68.92 (C-3), 62.68
(C-1'), 60.41 (C-5'), 58.61 (C-1); MALDI-TOF MS: m/e 428 (M+ + Na) ,406 (M+
+ H).
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SUBSTITUTE SHEET (RULE 26)

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5.2.5 Example 5 - General procedure for the deprotection of the protected
sulfonium sulfates (Schemes 7 - 10) and ammonium sulfates (Schemes 13 -
s The protected compound was dissolved in AcOH:H2O, 4:1 (3mL) and stirred
with Pd-C (80mg) under H2 (52 psi). After 60h the reaction mixture was
filtered through a pad of Celite, which was consequently washed with MeOH.
The combined filtrates were concentrated and the residue was purified by
column chromatography.
io
1-((1',4'-Anhydro-4'-thio-D-arabinitol)-4'-S-yl)-1-deoxy-L-erythritol-3-
sulfate (1 ).
Column chromatography [CHCI3:MeOH:H20, 7:3:1] of the crude product gave
an amorphous solid (67%). [a]p +2.1° (c 0.48, MeOH); ~H NMR (pyridine-
d5):
is 8 5.25 (1 H, ddd, J = 7.4, 3.8, 3.6 Hz, H-3), 5.14-5.09 (2H, m, H-3', H-
2'), 5.00
(1 H, m, H-2), 4.78 (1 H, dd, J = 13.0, 4.9 Hz H-1 a), 4.70 (1 H, m, H-4'),
4.63
(1 H, dd, J = 13.0, 4.0 Hz H-1 b), 4.61 (1 H, dd, J = 11.8, 3.7 Hz H-4a)4.53
(2H,
m, H-5'a, H-5'b),4.38 (1 H, dd, J = 11.8, 3.8 Hz H-4b), 4.32 (2H, br-s, H-1'a,
H-
1'b); ~3C NMR (100.6 MHz, pyridine-d5): 8 79.14 (C-3), 79.06 (C-3'), 78.18 (C-
20 2'), 72.30 (C-4'), 67.44 (C-2), 62.05 (C-4), 59.98 (C-5'), 52.46 (C-1 ),
50.35 (C-
1'). HRMS. Calcd for CgH~gOgS~ (M + H): 335.0471. Found: 335.0481.
1-((1',4'-Anhydro-4'-thio-D-arabinitol)-4'-S-yl)-1-deoxy-D-erythritol-3-
sulfate (23).
2s Column chromatography [CHCI3:MeOH:H20, 7:3:1] of the crude product gave
an amorphous solid (59%). [a]o -35.6° (c 0.86, MeOH); 'H NMR (pyridine-
d5): b 5.19 (1 H, ddd, J = 8.0, 4.1, 3.6 Hz, H-3), 5.17-5.12 (2H, m, H-2', H-
3'),
5.00 (1 H, ddd, J = 8.0, 5.3, 4.1 Hz, H-2), 4.83 (1 H, dd, J = 13.0, 5.1 Hz H-
1 a),
4.78 (1 H, m, H-4'), 4.65 (1 H, dd, J = 11.9, 3.8 Hz H-4a), 4.64-4.57 (2H, m,
H-
30 5'a, H-5'b),4.53 (1 H, dd, J = 13.0, 4.1 Hz H-1 b), 4.40 (1 H, dd, J =
11.9, 3.8 Hz
H-4b), 4.29 (1 H, dd, J = 12.7, 3.9 Hz H-1'a), 4.17 (1 H, dd, J = 12.7, 2.6 Hz
H-
1'b); ~3C NMR (100.6 MHz, pyridine-d5): b 79.46 (C-3), 79.38 (C-3'), 78.94 (C-
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SUBSTITUTE SHEET (RULE 26)

CA 02396688 2002-07-08
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2'), 71.94 (C-4'), 67.52 (C-2), 62.02" (C-4), 60.26 (C-5'), 52.64 (C-1 ),
51.01 (C-
1'). HRMS. Calcd for CgH~gOgS2 (M + H): 335.0471. Found: 335.0486.
1-((1',4'-Anhydro-4'-thio-L-arabinitol)-4'-S-yl)-1-deoxy-D-erythritol-3-
s sulfate (25).
Column chromatography [CHCI3:MeOH:H20, 7:3:1] of the crude product gave
an amorphous solid (80%). [a]p +1.1° (c 1.5, MeOH); ~H NMR (pyridine-
d5): 8
5.23 (1 H, ddd, J = 7.4, 3.8, 3.7 Hz, H-3), 5.11 (1 H, m, H-3'), 5.10 (1 H, m,
H-2'),
4.98 (1 H,m, H-2), 4.76 (1 H, dd, J = 11.7, 3.7 Hz H-1 a), 4.70 (1 H, m, H-
4'),
l0 4.63 (1 H, dd, J = 11.7, 3.8 Hz H-1 b), 4.60 (1 H, dd, J = 11.8, 3.7 Hz H-
4a)4.51
(2H, m, H-5'a, H-5'b),4.35 (1 H, dd, J = 11.8, 4.0 Hz H-4b), 4.31 (2H, m, H-
1'a,
H-1'b); ~3C NMR (100.6 MHz, pyridine-d5): 8 79.38 (C-3, C-2'), 78.41 (C-3'),
72.51 (C-4'), 67.63 (C-2), 62.23 (C-4), 60.21 (C-5'), 52.60 (C-1 ), 50.57 (C-
1')
HRMS. Calcd for CgH~gOgS2 (M + H): 335.0471. Found: 335.0466.
is
1-((1',4'-Dideoxy-1',4'-imino-D-arabinitol)-4'-N-yl)-1-deoxy-L-erythritol-3-
sulfate (2).
Column chromatography [CHCI3:MeOH:H20, 7:3:1] of the crude product gave
an amorphous solid (64%). ~H NMR (CD30D): 8 4.26-4.20 (2H, m H-2, H-3),
20 4.15 (1 H, m, H-2'), 3.98 (1 H,br-s, H-3'), 3.94-3.87 (3H,m, H-5'a, H-5b',
H-4a),
3.81 (1 H, dd, J = 12.0, 3.5 Hz H-4b), 3.74-3.62 (2H, m, H-1 a, H-1'a), 3.49-
3.42 (1 H, m, H-1'b),3.40-3.35 (1 H, m, H-4'), 3.15 (1 H, m, H-1 b); ~3C NMR
(100.6 MHz, CD30D): 8 81.17 (C-3), 78.27 (C-3'),77.86 (C-4'), 76.19 (C-2'),
68.07 (C-2), 62.57 (C-1'), 61.67(C-4), 60.72 (C-1, C-5'). HRMS. Calcd for
2s CgH~gOgSN (M + H): 318.0859. Found: 318.0863.
1-((1',4'-Dideoxy-1',4'-imino-L-arabinitol)-4'-N-yl)-1-deoxy-D-erythritol-3-
sulfate (32).
Column chromatography [CHCI3:MeOH:H20, 7:3:1] of the crude product gave
an amorphous solid (77%). ~ H NMR (CD30D): 8 4.25 (1 H, m H-2), 4.23(1 H,
m, H-3), 4.16 (1 H, br-s, H-2'), 3.99 (1 H,br-s, H-3'), 3.94-3.87 (3H,m, H-
5'a, H-
5b', H-4a), 3.81 (1 H, dd, J = 12.1, 3.6 Hz H-4b), 3.77-3.64 (2H, m, H-1 a, H-
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CA 02396688 2002-07-08
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1'a), 3.55-3.39 (2H, m, H-1'b, H-4'), 3.22 (1 H, m, H-1 b); ~3C NMR (100.6
MHz,
CD30D): 8 81.18 (C-3), 78.23 (C-3', C-4'), 76.10 (C-2'), 68.05 (C-2), 62.66 (C-
1'), 61.88(C-4), 60.49 (C-1, C-5'). HRMS. Calcd for CsH~sO9SN (M + H):
318.0859. Found: 318.0856.
s
As will be apparent to those skilled in the art in the light of the
foregoing disclosure, many alterations and modifications are possible in the
practice of this invention without departing from the spirit or scope thereof.
Accordingly, the scope of the invention is to be construed in accordance with
to the substance defined by the following claims.
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SUBSTITUTE SHEET (RULE 26)

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References:
1. Yoshikawa, M. et al. Tetrahedron Lett. 1997, 38(48), 8367 - 8370.
s 2. Yoshikawa, M. et al. Chem. Pharm. Bull. 1998, 46(8), 1339-1340.
3. Shimoda, H. et al. Journal of the Food Hygienic Society of Japan. 1999,
40(3), 198-205.
4. Goss, P.E. et al. Clinical CancerRes. 1997, 3, 1077-1086.
5. Mohla, S. et al. Anticancer Res. 1990, 10, 1515-1522.
l0 6. Goss, P.E. et al. CancerRes: 1994, 54, 1450-1457.
7. Eames, J. et al. Tetrahedron Lett. 1998, 39(10), 1247-1250.
8. Calvo-Flores, F.G. et al. J. Org. Chem. 1997, 62, 3944-3961.
9. Foster, A.B. et al. J. Chem. Soc. 1961, 5005-5011.
10. MacDonald, D.L. et al. J. Am. Chem. Soc. 1956, 78, 3720-3722.
is 11. Yoshimura, Y. et~al. J. Org. Chem. 1997, 62, 3140-3152.
12. Satoh, H, et al. Bioorg. Med. Chem. Lett. 1998, 8(9), 989-992.
13. Fleet, G. et al. Tetrahedron. 1986, 42, 5685-5692.
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SUBSTITUTE SHEET (RULE 26)

Representative Drawing